Thyroid cancer is a condition in which malignant cells form in the tissues of the thyroid gland. Thyroid cancer is the most prevalent endocrine malignancy and has been increasing in incidence over recent decades. Fortunately, with early detection and appropriate treatment, the prognosis for most types of thyroid cancer is excellent.
There are several types of thyroid cancer, each with its own distinctive characteristics. About 90% of thyroid cancers are differentiated thyroid cancers.
Differentiated thyroid cancers comprise of:
- Papillary thyroid cancer – This is the most common type of thyroid cancer, accounting for approximately 80% of all cases. It is more common in women and usually occurs in people in their 30s-40s. It typically grows slowly but may spread to lymph nodes in the neck or close to the thyroid.
- Follicular thyroid cancer – This is the second most common type of thyroid cancer and usually affects people in their 40s-60s. Follicular thyroid cancer sometimes spreads to distant organs, such as the lungs or bones.
Other less common types of thyroid cancer include:
- Medullary thyroid cancer - This is a rare type of thyroid cancer which starts in the parafollicular C cells in the thyroid. About 25% of medullary thyroid cancer is hereditary due to a faulty thyroid gene which runs in the family.
- Anaplastic thyroid cancer – This is a very rare and aggressive form of thyroid cancer, usually diagnosed in older people. It is called undifferentiated thyroid cancer as the cancer cells do not look like normal thyroid cells. It tends to grow more quickly and may present at a more advanced stage.
- Thyroid lymphoma – This is a type of non-Hodgkin lymphoma and treatment is similar to that of a lymphoma.
Symptoms of thyroid cancer
Most thyroid cancers are asymptomatic in the early stages and are often discovered incidentally on imaging studies or during evaluation of a neck mass.
When symptoms are present, they may include:
- A painless lump or swelling in the neck
- Hoarseness or voice changes that don’t go away.
- Difficulty swallowing
- Breathing problems if the tumour presses on the windpipe.
- Swollen lymph nodes in the neck
Diagnosis
Evaluation of a thyroid nodule typically begins with a neck ultrasound, followed by a fine-needle aspiration (FNA) biopsy if the nodule or nodules appear suspicious. Additional imaging, such as CT, MRI or radioactive iodine scans may be used to assess the extent of disease. Blood tests including thyroid function tests are also important in diagnosis and monitoring.
Treatment options
Treatment is highly individualised and depends on the type of thyroid cancer, the size and whether it has spread to other parts of the body.
Treatment options include:
This is the primary treatment for most cancers and will involve the Thyroid Surgeon who will discuss with you on the surgical options – lobectomy (removal of part of the thyroid) or total thyroidectomy.
Thyroid hormone replacement would be required after total thyroidectomy and this method of thyroid hormone suppression helps to reduce the risk of cancer recurrence by lowering TSH levels.
This may be used in aggressive or unresectable tumours.
